DULUTH — A woman watches her dog do its business and briefly considers abandoning her duty to pick it up when a sort of superhero appears and brusquely reminds her, "There's no poop fairy to do that for you."

That's the gist of a new ad campaign released Friday to remind pet owners their dog waste can contaminate streams and lakes to an unhealthy degree.

"I believe that gently chiding wayward dog owners is a good way to bring attention to the problem without necessarily shaming people or scolding them," said Lucie Amundsen, public information officer for the Minnesota Pollution Control Agency in Duluth, which is one of the groups behind the campaign. "If you know better you do better.

The brief video uses potty humor to preach clean watersheds and remind pet owners there are thousands of dogs in the region creating millions of pounds of waste every year. The poop fairy campaign started in Duluth parks this summer as cities have been getting increasingly creative to combat unscooped poop.

"It's not just the waste of one dog that creates a problem," said Andrea Crouse, Regional Stormwater Protection Team co-chair and city of Superior water resources program coordinator. "If we're not considering the cumulative impact of all this pet waste on our relatively pristine rivers and Lake Superior, then it is going to end up being a death of that water quality by not a thousand paper cuts but a thousand poops."

The beach closures and dozens of E. coli cases on Lake Nokomis in Minneapolis this summer should serve as a warning of what could happen if waste continues to build up unabated, though bird feces also plays a large role in bacteria buildup.

The trouble with dog doo is the nutrients it releases into the water that feed unwanted algae, which can warm waters and choke out native fish populations. The runoff from animal waste can also foster harmful bacteria and pathogens and sicken humans.

It's not always the bacteria itself that is dangerous, but what it says about the water quality, Crouse said.

Duluth is taking a look at E. coli levels in Keene Creek, which flows through western neighborhoods and along a dog park on its way to the St. Louis River. When the data comes in, it could be a telling sign of the poop fairy's effectiveness on social media and signs the video campaign is now piggybacking on.

"It has done a good job generating conversations," Duluth Parks and Recreation Manager Jessica Peterson.

On top of the advocacy work, the city spends $10,000 a year on "mutt mitts" placed at trailheads and parks throughout Duluth.

"It's not a small amount of money to invest trying to help citizens make the right decisions," which include the crucial final step of bringing the waste to a garbage can, Peterson said.

And while it's tempting to let the snow bury your dog's bathroom break, she warned that decision makes for a messy spring and a high concentration of unwanted nutrients flowing into area streams.

Crouse said the timing of the poop fairy video should get the message out before those winter habits return. She also hopes word spreads beyond parks and trails to remind pet owners to scoop on sidewalks, too, since waste can reach the Big Lake even faster through stormwater systems.

"We might feel disconnected from the water depending on where we live in the community," Crouse said, "but just because we live in an urban environment doesn't mean we're not connected to Lake Superior."

Brooks Johnson • 612-673-4229